Hitch assemblies provide a connection between a device, such as a trailer, ski rack, or the like, and a vehicle. A receiver-type hitch assembly typically includes a receiver that is attached to the frame of a vehicle and a hitch that is removably inserted into the receiver. The hitch may include, for example, a conventional trailer ball that is sized to be engaged by a ball receiver on a trailer. Alternatively, the hitch may comprise a portion of a carrier, for example, a bicycle carrier, ski carrier, cargo carrier, or the like. The hitch may include additional or alternative mechanisms for engaging an apparatus to be carried or towed. A conventional SAE receiver typically comprises a rectangular tube with a rearwardly facing square opening that is 1.25 inches (32 mm), 2.0 inches (51 mm) or 2.5 inches (64 mm) square.
The insertable hitch includes a shaft having an outer dimension that is somewhat smaller than the inner dimension of the receiver so that the hitch can be relatively easily inserted into the receiver. A hitch pin (or locking pin) is inserted through holes provided in the side walls of the receiver and alignable holes in the hitch. The locking pin may be secured, for example, with a retaining clip to prevent the locking pin from inadvertently coming out during use. Exemplary prior art hitch assemblies include those disclosed in U.S. Pat. No. 6,105,989, to Linger, which is hereby incorporated by reference in its entirety, and in U.S. Pat. No. 6,382,656, to Johnson, Jr., which is hereby incorporated by reference in its entirety.
Detachable hitches are preferred for many applications. For example, a user may use one hitch for towing loads and other hitches for attaching bicycle racks, ski racks, carriers, or the like, to the vehicle. Also, hitches typically extend beyond the rear of the towing vehicle to enable attachment of a trailer to the hitch with clearance for the trailer and towing vehicle to articulate relative to each other during towing. The protruding hitch with a ball attachment can be bothersome and dangerous when the vehicle is used without the trailer attached; therefore, it is beneficial to be able to remove the hitch when it is not needed.
However, as noted above the hitch shaft is smaller than the receiver opening, and so the fit between the hitch and the receiver includes some play between the receiver and the walls of the hitch shaft. The relatively loose fit permits undesirable relative movement or play between the receiver and the hitch, which can be noisy and annoying. The play between the walls of the receiver and hitch can cause clanging noises and vibrations that can be felt by operators and passengers within the towing vehicle. The play may also be magnified by the lever arm of the hitch so that it is felt more strongly by the trailer. That same play can also increase wear and stress on various parts of the mechanisms attaching the trailer to the towing vehicle, leading to undesirable wear and fatigue.
The disadvantages of the relatively loose fit between the receiver and hitch coupling have been recognized by others. For example, in U.S. Pat. No. 6,974,147, to Kolda, which is hereby incorporated by reference, a mechanism for preventing relative movement between these members is disclosed, wherein the tow bar or mounting member is provided with a cam that is adjustably urged into the mounting member and abuts the hitch pin. The adjustment mechanism causes the cam to rotate, extending through a slot in the mounting member, and is urged against the receiver. However, the mechanism has the disadvantage that it presses against the receiver at a single position and against the opposite side of the mounting member at a single position, in addition to the hitch pin, which may still permit some movement between the mounting member and receiver.